During the last years short fiber reinforced thermoplastics have become more and more interesting for example when used for parts that underlay high stresses. To utilize all the properties of these injection molded component parts it is normally necessary to carry out an extensive development and pre-design. Two of the major problems are the high costs and the amount of time these developments normally take. Accordingly the simulation of short fiber reinforced thermoplastics became more and more interesting. The performance of the newest computers does no longer represent a big problem for the simulation. The weakest point of the calculation is the selection of the material laws and also their experimental determination. It is shown how it is possible to implement the fiber orientation - simulated with injection molding simulation programs (Cadmould, Moldflow and C-Mold) - into a stiffness or creep analysis on Polybutylenterephthalate with 30% glass fibers (PBT-GF30) and Polyamide 6.6 with 25% glass fibers (PA66-GF25). In the following it is necessary to determine the elastic and creep behavior of a composite with unidirectional orientated fibers. On one side it is possible to calculate these properties using micro-mechanical material models (such as the Halpin-Tsai-Equation). But the simplified terms of these calculations normally lead to a result that describes the mechanical behavior too stiff. So it seems on the other side more useful to determine the elastic and the creep behavior using experimental data. The following simulations on simple test specimens show that it is possible to simulate the elastic behavior with good exactness. The error of these simulations is under ten percent. The creep behavior can be simulated in two different ways. On one hand an isotropic calculation is standard at the moment. The composite is described in every direction with the same creep equation. On the other hand the creep behavior can be simulated in an anisotropic way. The simulation-programs do not allow a direct implementation of the four transversal isotropic creep equations. The simulation of the creep behavior can be carried out with the help of the Hill-Potential by which an anisotropic equivalent stress can be defined. When it is possible to implement the right fiber orientation the error of these anisotropic creep-simulations is under fifteen percent. The anisotropic simulation method developed at the test samples was transferred to a construction component, but the error of these simulations is 40 percent. The reason for the still not good enough results of the component simulation is the too inaccurate simulation of the fiber orientation. At the moment the simulation programs are not able to calculate the fiber orientation in an accurate way. Though the exact simulation of the creep behavior of complex components is not possible, the developed simulation method gives engineers a practical possibility to estimate the creep behavior of short fiber reinforced thermoplastics.